Powertrain electric control units (ECUs) for vehicles, such as commercial vehicles, often utilize high side drivers as voltage sources for one or more loads. High side drivers are outputs located on a high voltage side of the load. In a typical example, the high side driver is controlled by a pre-drive integrated circuit (IC). The pre-drive IC is configured by a processor, such as a local microprocessor or an engine controller. With certain loads, when the load is added or switched on, a load capacitance is added to the overall circuit. By way of example, smart actuators that are present in many commercial vehicle loads include a large inbuilt capacitance. Alternatively a battery, or other power storage device, can be included within the load and may need to be charged.
In such instances, an initial inrush current related to charging the capacitance or the power storage device can occur. This inrush current can, in some examples, exceed a fault current threshold included within a fault detector and cause a false over-current fault detection by the fault protection device. When an over-current fault is detected, the fault protection device disables the output of the high side driver and prevents current from reaching the loads.
Some existing systems prevent false detection of an over-current fault by utilizing smart output FETs within the high side current driver. Smart output FETs are expensive and can be cost prohibitive. Alternative existing systems utilize discrete circuits to prevent false fault detections. Discrete circuits capable of performing this function are physically large and can be space prohibitive.